The present invention relates to surgical sutures, and more particularly, to soft, elastomeric sutures having unique handling and knot tying characteristics. The sutures may be prepared from segmented copolyether/esters or other elastomeric polymers.
Many natural and synthetic materials are presently used as surgical sutures. These materials may be used as single filament strands, i.e, monofilament sutures, or as multifilament strands in a braided, twisted or other multifilament construction. Natural materials such as silk, cotton, linen, and the like, of course do not lend themselves to the fabrication of monofilament sutures and are accordingly generally used in one of the multifilament constructions.
Synthetic materials which are extruded in continuous lengths can be used in monofilament form. Common synthetic monofilament sutures include polyethylene terephthalate, polypropylene, polyethylene, and nylon. Such monofilament sutures are preferred by surgeons for many surgical applications due to their inherent smoothness and noncapillarity to body fluids.
The presently available synthetic monofilament sutures all suffer to a greater or lesser degree from one particular disadvantage, that is inherent stiffness. Besides making the material more difficult to handle and use, suture stiffness can adversely affect knot tying ability and knot security. It is because of the inherent stiffness of available monofilament sutures that most larger suture sizes are braided or have other multifilament constructions with better handling flexibility.
Monofilament sutures of the prior art are also characterized by a low degree of elasticity, the most elastic of the above-mentioned synthetics being nylon which has a yield elongation of about 1.7 percent and a viscoelastic elongation of about 8.5 percent. The inelasticity of these sutures also makes knot tying more difficult and reduces knot security. In addition, the inelasticity prevents the suture from "giving" as a newly sutured wound swells, with the result that the suture may place the wound tissue under greater tension than is desirable, and may even cause some tearing, cutting or necrosis of the tissue.
The problems associated with the use of inelastic sutures in certain applications were recognized in U.S. Pat. No. 3,454,011, where it was proposed to fabricate a surgical suture composed of Spandex polyurethane. Such sutures, however, were highly elastic with "rubbery" characteristics and did not find general acceptance in the medical profession.
It is accordingly an object of the present invention to provide a novel soft, limp, monofilament suture material. It is a further object of this invention to provide a monofilament suture with a controlled degree of elasticity to accommodate changing wound conditions. It is another object of this invention to provide a new, nonabsorbable suture having a diameter of from about 0.01 to 1.0 mm and possessing unique and desirable physical properties. These and other objects will be made apparent from the ensuing description and claims.